For reasons of operational safety and availability of motor vehicles, components critical to safety and whose function is absolutely necessary for the operation of the vehicle are increasingly provided in a redundant configuration. This applies especially to devices for detecting the position of an accelerator pedal and/or a power-determining element of the engine or of the motor vehicle.
Published German patent application 3,539,407 discloses providing two of each of the following: a measuring device for detecting the position of a power-determining element, a desired-value transducer, an engine-speed transducer and the transducer detecting the position of the brake pedal.
U.S. Pat. No. 4,603,675 discloses an electronic accelerator-pedal system for a motor vehicle wherein the measuring device for detecting the position of an operator-actuated element are provided in a twin configuration. Here, either two potentiometers detecting the position or a potentiometer-switch combination is provided. A fault condition in the area of the accelerator pedal, the measuring devices and/or their connecting lines to the control system can be determined by means of a comparison of the signal values generated by the twin measuring devices to a pregiven tolerance band. A fault condition is recognized when the signal values do not lie within this tolerance band. The system then transfers to an emergency-operating mode when a fault is detected.
When a fault condition is detected, an emergency operation limiting the use of the motor vehicle is introduced because in such devices safety considerations are of primary importance. This limited availability is however a serious disadvantage of the known systems.